Re: [Qemu-discuss] Multiple snapshots with one guest user

From:

Alberto Garcia

Subject:

Re: [Qemu-discuss] Multiple snapshots with one guest user

Date:

Wed, 25 Jan 2017 09:38:32 +0100

User-agent:

Mutt/1.5.23 (2014-03-12)

On Thu, Jan 19, 2017 at 03:20:33PM +0330, Mahmood Naderan wrote:
> May i ask what is the difference between the following commands
>
> 1) qemu-img create -o backing_file base.img new.img 10G
> 2) qemu-img create -f qcow2 -b base.img new.img
There's several things here:
# "-o backing_file=base.img" and "-b base.img" are equivalent.
# In (1) you're missing the '=' in backing_file=base.img
# If (1) you're also not specifying the file format, then it
defaults to raw. But raw does not support backing files, so the
command will not work.
# qcow2 does support backing files, that's why (2) works.
Berto